By default, the DMA mask covers only the low 32-bit address space, which
causes SWIOTLB on arm64 to fall back to a bounce buffer for DMA
transfers involving memory outside the 32-bit address space.
The R-Car DMA controller hardware supports a 40-bit address space, hence
widen the DMA mask to 40 bits to actually make use of this feature.
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
Note that for proper operation in the presence of an enabled IOMMU, you
also need commit 3b6bb5b705a4051c ("iommu/ipmmu-vmsa: Restrict IOMMU
Domain Geometry to 32-bit address space") in iommu/next.
However, as the IOMMU is not enabled in upstream nor linux-next, it is
safe to apply this patch in parallel.
v2:
- No changes.
---
drivers/dma/sh/rcar-dmac.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 2e441d0ccd79a37a..93a69b992a51a7aa 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -1716,6 +1716,7 @@ static int rcar_dmac_probe(struct platform_device *pdev)
dmac->dev = &pdev->dev;
platform_set_drvdata(pdev, dmac);
+ dma_set_mask_and_coherent(dmac->dev, DMA_BIT_MASK(40));
ret = rcar_dmac_parse_of(&pdev->dev, dmac);
if (ret < 0)
--
1.9.1
